Spot-bonded mats and process for their manufacture

ABSTRACT

Improvements in producing a bonded non-woven fabric matting where the bonding agent is located in discontinuous areas of the matting or is present in differing and varying proportions in different areas of the matting. Such a product is made by substantially uniformly impregnating the matting with a heat sensitive coagulatable binder latex, non-uniformly heating the impregnated matting to the coagulation temperature of the latex only in predetermined areas of the matting whereby coagulating the binder from the latex only in the preselected areas which have been subjected to heating to a temperature sufficient to coagulate binder from the latex, and then removing that portion of the latex from which the binder was not coagulated by the nonuniform heating.

United States Patent [191 Petersik et al.

[4 Oct. 16, 1973 SPOT-BONDED MATS AND PROCESS FOR THEIR MANUFACTURE [75Inventors: Peter Petersik, Luetzelsachsen;

Rudolf Gaertner, Weinheim, both of Germany [73] Assignee: Firma CarlFreudenberg,

Weinheim, Germany [22] Filed: Jan. 28, 1971 [21] Appl. No.: 110,576

Related US. Application Data [63] Continuation-impart of Ser. No.848,460, Aug. 8,

1969, abandoned.

[30] Foreign Application Priority Data Apr. 24, 1969 Germany P 19 20836.7 Feb. 4, 1970 Germany P 20 04 988.1

[52] US. Cl. 156/84, 117/38, 117/42,

[51] Int. Cl..... B32b 31/20, 1332b 31/22, B32b 3/30 [58] Field ofSearch 161/148, 170; 117/38, 42, 62, 62.2, 63; 156/155, 209, 84,

3,698,973 10/1972 Wisotzky et a1. 156/321 X 3,708,366 l/ 1973 Donnelly156/209 3,717,528 2/1973 Peerman et aL... 156/155 X 3,704,191 11/1972Buresh et al 156/209 X 3,424,604 l/ 1969 Fukushima et al. 117/633,459,627 8/1969 Vosburgh 156/209 X 2,719,806 10/1955 Nottebohm 171/170X 2,880,113 3/1959 Drelich 161/148 X 2,940,871 6/1960 Smith-Johannsen 117/63 2,983,960 5/1961 Jilge 156/155 X 3,245,863 4/1966 Sonnichsen eta]. 156/84 X 3,293,095 12/1966 Pitzer 156/155 Primary Examiner--HaroldAnsher Attorney-Burgess, Dinklage & Sprung [5 7] ABSTRACT Improvementsin producing a bonded non-woven fabric matting where the bonding agentis located in discontinuous areas of the matting or is present indiffering and varying proportions in different areas of the matting.Such a product is made by substantially uniformly impregnating thematting with a heat sensitive coagulatable binder latex, non-uniformlyheating the impregnated matting to the coagulation temperature of thelatex only in predetermined areas of the matting whereby coagulating thebinder from the latex only in the preselected areas which have beensubjected to heating to a temperature sufficient to coagulate binderfrom the latex, and then removing that portion of the latex from whichthe binder was not coagulated by the non-uniform heating.

8 Claims, 8 Drawing Figures Patented Oct. 16, 1973 2 Shanta-43km. l

FIGS

Perm s// ET AL.

Patented Oct. 16, 1973 2 Sheets-Sheet It FIG.6

INVENTOR PETER PETERSIK\ ET AL SPOT-BONDED MATS AND PROCESS FOR THEIRMANUFACTURE This application is a continuation-in-part of ApplicationSer. No. 848,460, filed Aug. 8, 1969, now abandoned.

This invention relates to non-woven fabrics. It more particularly refersto non-woven fabrics which are particularly useful for synthetic leatheror leather-like applications.

Non-woven fabrics, as this term is used in the textile arts, are mats orbats made up of staple fibers or continuous filaments where theindividual fibers or portions of the individual filaments aregeometrically randomly disposed with respect to each other. Such fabricsare usually made from a card lap (in the case of staple fibers) whichmay or may not have been passed through a cross lapper and/or a needleloom in order to further disorient the fibers with respect to eachother. Non woven fabrics made up of continuous filaments are often madeby laying the filaments down on a suitable fleece form directly out ofthe spinnerette in a random pattern. The term non-woven does not includeknitted, netted, crocheted or other fabrics having fibers or filamentsin a geometrically patterned array, regardless of how made.

In any case, regardless of how the randomlay, nonwoven fabric is made,and regardless of whether such fabric is composed of staple fibers orcontinuous filaments, it is common in this art to bond in some way theindividual fibers or filament portions together so as to increase thedimensional stability of the mat or bat product to an extent sufficientto create a fabric having physical integrity. Such bonding has beenaccomplished in the past by many varying techniques, includmg:

l. providing at least some thermoplastic fibers or filaments in thefabric having a lower melting or softening point than the remainder ofthe fibers or filaments and then heating the fabric to an extentsufficient to melt or at least tackify these fibers or filaments andcause them to bond to other fibers and- /or filaments;

2. uniformly impregnating the non-woven fabric with a liquid formbonding agent, either solution or latex, and removing the carrier liquidthereby depositing bonding agent throughout the fabric which effectivelybonds the fibers or filaments together;

3. spot impregnating the non-woven fabric and proceeding as in 2); or

4. providing a plasticizer or other softening agent uniformly orspotwise through the non-woven fabric in an amount sufficient to causethe fibers or filaments of the fabric to become tacky to an extentsufficient to bond them together.

In all of these techniques the bonding generally takes place at thecrossing points of the fibers or filaments, thereby retaining thetextile and sometimes lofty character of the fabric.

In the manufacture of non-woven textile fabrics in the prior art theuniformly impregnated loose fiber mats were dried, in which dryingprocess the binding agent collected in the form of lamella or websmainly at the intersections between the fibers or filaments, as canclearly be seen in FIG. 4 of U.S. Pat. No. 2,719,802. The binding agentin this lamella form was vulcanized by the action of heat simultaneouslywith the drying of the fabric. The products thus manufactured, which arecommercially available (under the name Vlieseline in Germany, or Pellonin the United States) are especially characterized by their springinessand elasticity. They are therefore used mainly as lining and stiffeningmaterials in clothing.

From U.S. Pat. No. 2,545,952, it is furthermore known to imprint upon aninitially loose non-woven mat fabric spots of rubbery latex or otherbinding agent having similar properties, such as casein, glue, naturalresins, etc., making use of a roll engraved with spot depressions forthe purpose. The binding agent, which is at first imprinted as spots onthe surface of the mat, then sinks slowly into the interior of the matso that a bonding action is produced also in areas underneath theimprinted surface spot of latex. This method, which is suitable only inthe case of thin matting weighing up to about 60g/m is also known inGermany by the English term spot binding. Also see in this connectionWest German Auslegeschriften Nos. 1,098,903, 1,099,983, 1,106,285, and1,062,204.

The spot-bonded non-woven fabrics known hitherto are softer and morewater-absorbent than otherwise equivalent mats which are uniformlyimpregnated with binding agent. However, their tensile strength is low,as might be expected, and therefore they are usually used for themanufacture of disposable goods.

Clearly, it would be desirable to provide non-woven textile fabricswhich have the water-absorbency characteristics of spot-bonded fabricsand the tensile properties of uniformly bonded fabrics. It would also bemore desirable to be able to utilize non-woven fabrics having a fiberweight of higher than about 60 grams per meter, which is about thehighest weight fabric the prior art has been able to work with in aspot-bonding technique, such as higher fiber weights being for example,up to about 1000 grams per meter or even more.

The objects of this invention are, therefore, to fulfill theabove-recited desirable conditions.

In accord with, and fulfilling these objects, one aspect of thisinvention resides in a novel technique of bonding a non-woven fabric.According to this invention, a suitably formed non-woven fabric ofstaple fibers or of continuous filaments is substantially uniformlyimpregnated with a latex form bonding agent which is coagulationsensitive as a function of temperature. Such so-called heat-sensitive,coagulatable latexes are known, and it is per se known to impregnate anonwoven fabric therewith, according to U. S. Pat. No. 2,719,802. Byheat-sensitized, bonding agents are meant those in which the bondingagent abruptly flocculates (coagulates) in the form of tiny spheres orbeads when a predetermined certain temperature, e.g., about 20 to C,preferably 40 to 60C, is applied. This type of heat sensitive bondingagent is commercially available and is a per se well-known product. Thethus substantially uniformly impregnated non-woven fabric is thensubjected to a procedure whereby binder is caused to deposit only inpredetermined locations.

The impregnated fabric is passed through heating means which may be anunheated smooth roller or a flat plate on one side and a heated rolleron the other side which heated roller has protuberances on the surfacethereof. The protuberances heat those portions of the fabric which theycontact or which they approach to a greater degree faster than thoseportions of the fabric which are disposed opposite the areas between theprotuberances. Therefore, the residence time or contact time between theimpregnated fabric and the heated roller protuberances and thetemperature of the heated roller protuberance can be so adjusted withrespect to each other and with respect to the coagulation temperature ofthe latex impregnant that the area of coagulation of the binder from thelatex can be very carefully controlled. It is not necessary to thepractice of this aspect of this invention that theprotuberancecontaining roller be heated in its entirety, although thisis possible and in many cases may be the most practical solution toeffecting the localized heating; the roller therefore may be constructedin such a manner that only the protuberances are heated. The roller maybe heated by any conventional technique, e.g., electric resistance,steam, heating liquids, direct fired heat or the like. Whether theroller acts as a heat exchanger by having heating means as an integralpart of its construction or by its being heated away from the fabric andthen passing the heat on to the fabric is immaterial to this aspect ofthis invention. What is important is only that at least theprotuberances of the roller means are heated to a high enoughtemperature and are juxtaposed to the fabric for long enough to causethe binder to coagulate in certain preselected areas of the fabric butinsufficient to cause the binder to coagulate in other, adjacent areasof the fabric.

It should be appreciated that the latex coagulation temperature, theroller protuberance temperature and the juxtaposition time are allinterrelated functions and they cannot be individually defined withoutreference to the other. That is, for a given latex having a givencoagulation temperature, a certain protuberance temperature, aparticular juxtaposition time and a given spacing between fabric aNdprotuberance (including zero spacing which would define simple contactor even negative spacing which would define contact accompanied bypressing of the fabric by the protuberances) are required to causecoagulation of bonding agent from the latex only in the requiredpredetermined spots or areas where it is desired.

The routineer in the art, given the interrelations expressed above, andknowing the coagulation temperature of the latex as well as the area oflatex to be coagulated by each protuberance, can easily calculate therequired parameters of spacing, juxtaposition time and protuberancetemperature sufficient to cause such coagulation in such predeterminedareas. General operating parameter ranges are: protuberance temperature120 to 420 C, protuberance/fabric juxtaposition time 0.1 to 3 seconds.It will be appreciated, however, that there will be readily foundoperating parameter combinations suitable for the purposes of thisinvention which are outside the scope of one or more of the ranges setforth above. The only critical parameter is that the operation besufficient'to cause predetermined areas of binder to coagulate whilepreventing the remainder of the binder from coagulating.

Another aspect of this invention which will accomplish the coagulationof binder in predetermined areas of a non-woven fabric while preventingor minimizing the coagulation of binder in other areas of the fabric isto pass a substantially uniformly impregnated non woven fabric throughthe nip of a pair of roll means wherewith the roll means havealternating protuberances thereon, or where one roll has protuberancesand the other is smooth. As the impregnated non-woven fabric passesbetween the rolls, the action of the alternating protuberances exerts apressure on the fabric and on the latex impregnated therein toeffectively force some or all of the latex into areas between nextadjacent alternating protuberances. This action effectively localizesthe latex impregnant into predetermined areas from which the binder isthen coagulated by subjecting the thus treated fabric to uniformlocalized heating as the case may be. If heating sufficient to coagulatebinder from the heat-sensitive latex is instituted immediately aftertreatment by the protuberance roll means, the liquid form latex will nothave time to flow back to a uniform impregnation condition before thebinder is coagulated therefrom. Thus the binder can be coagulated anddisposed substantially only in those areas where it is desired. It iswithin the scope of this invention to use heated roll means or toprovide separate heating means following the protuberance roll means.

By adjusting the nip pressure of the protuberance roll means it ispossible to control the proportion of binder which will be forced out ofthose areas impressed by the protuberances into the areas betweenprotuberances. By controlling this pressure, all or only part of theimpregnated binder can be moved as desired.

Although it is considered to be less desirable, the protuberances on thepressure-exerting roll can be in mating configuration as well asalternating configuration.

In all aspects of this invention, regardless of how the latex is movedwithin the non-woven fabric or how spotwise coagulation is accomplished,after coagulation of the binder, the fabric is then treated to removeany remaining uncoagulated binder from the fabric. This can beaccomplished by simply washing the coagulated binder containinglatex-with water.

It has been found that the product produced by the above-describedprocess is quite unique. This uniqueness manifests itself in the factthat the final spotbonded product does not have a uniform thickness andthe fact that at least one of the major surfaces of the fabric productis profiled, that is, it has hills and valleys corresponding to thebinder-containing areas and the areas of low or no binder concentration.One of the surprising things about the product is that the surface.valleys do not correspond to those portions of the fabric which werejuxtaposed to the coagulating protuberances during binder-impregnationand coagulation but rather correspond to those portions of the fabricwhich were between these protuberances.

While not wishing to be bound by any particular theory, it is thoughtthat the valley portions of the spotbonded product are the result of apartial collapse of the unbonded non-woven fabric structure on washingout the uncoagulated binder while the hill portions correspond to thebinder-containing portions of the fabric because these portions havegreater resilience and dimensional stability.

Understanding of this invention will be facilitated by reference to thedrawing in which:

FIG. 1 is a schematic side elevation of a uniformly impregnated battingbeing juxtaposed to a protuberance containing heated roller;

FIG. 2 is an enlargement of the contacting portion of the roller andbatting of FIG. 1, schematically showing collimated coagulation withinthe batting;

FIG. 3 is a schematic side elevation of a batting having spot-coagulatedbinder therein as it leaves the coagulation process;

FIG. 4 is a schematic side elevation of the spotimpregnated productafter washing;

FIG. 5 is a schematic side elevation of a uniformly impregnated battingbeing treated with two opposing protuberance-containing rollers; and

FIG. 6 is an enlarged side elevation of the rollers of FIG. 5;

FIGS. 7 and 8 show examples of the surface of mats that have beenspot-bonded according to the invention.

Referring now to the drawing, a roller 1, having protuberances 2 ofgiven predetermined size, configuration and spacing, is rolled over abatting 3 just touching the batting, which was previously uniformlyimpregnated with the heat-sensitized binding agent, using a flat plateor table 1a as a base. In this depicted aspect of this invention, onlythe protuberances 2 of the roll 1 press against the batting 3, as it canbe seen in FIG. 1. As shown in FIG. 2, the heat of the protuberance 2 istransferred to the batting by radiation and conduction such that thebinding agent which is uniformly distributed in the batting, coagulatesonly in those areas of the batting where it has been heated by theprotuberance to a coagulating temperature, e.g., in the darker areashown in FIG. 2.

The heat radiated into the batting symbolized by arrows in FIG. 2 is sointense in the juxtaposed area of the batting that after about 1 secondof contact the binding agent coagulates (flocculates) in the areasdirectly below the protuberance 2. Heat also radiates into the battingfrom the adjacent areas 4 (recesses) of the roll, but the spacing of therecesses from the batting and the short contact time are so chosen thatthe combination is insufficient to heat that portion of the impregnantto a temperature which is sufficiently high to cause coagulation(flocculation) of the binder. The pressure exerted by the roll 1 on thebatting 3 and the roll temperature are so chosen to produce the aboveheating and coagulation effect and the effective contact time betweenthe roll and the mat is preferably maintained at only about 1 second atboth the leading and trailing edges of the protuberances. Consequently,when the protuberance 2 touches the fabric 3 only the binding agent inthe area 3a will coagulate, while the binding agent in the adjacentareas 4' and 4 will not coagulate at all or will coagulate only to asignificantly lesser extent. This selective coagulation process isrepeated constantly as the hot roll 1 passes over the uniformlyimpregnated batting. Substantially immediately or as soon as it issufficiently heated after the juxtaposing of protuberance 2 against thebatting 3, the binding agent directly under the contact surface in thebatting coagulates, but it does not coagulate in the areas immediatelyadjacent thereto. The cross-section of coagulated binder in FIG. 2 hasbeen shown to be rectangular. Actually it will probably be more conical,or possibly eliptical; however, since the fabric thickness is so smallthe actual cross-section is most difficult to determine.

If the pressure between the roll 1 and the fabric 3 is such that theprotuberances 2 press into the fabric 3, the binding agent latex will beforced out from immediately below the protuberances into the intersticesof the fabric disposed between protuberances (see areas marked 4' and 4"in FIG. 2). The heated roll will cause such displaced latex to coagulatein these areas 4' and 4" provided the contact time, the temperature andpressure of the roll are appropriately adjusted. Thus,

since the heat passage from the roll to the latex takes longer than thetime to displace the latex, short contact times and relatively high rollpressure will cause displacement and coagulation to occur sequentially.

After the passing of the hot roll 1, some of the binding agent in thebatting 3 is in the coagulated state and some remains uncoagulated. FIG.3 is a diagrammatic representation of such a batting. It can be seen howareas 3a containing coagulated binding agent alternate with areas 41a inwhich the binding agent is present in the uncoagulated form. When thebinding agent coagulates from a latex, it separates in the form of manysmall spherules, which is the reason why the structure is often referredto as a caviar or birdshot structure. It is for this reason that thestructure of the coagulated binding agent is represented by dots in FIG.3. The uncoagulated binding agent is represented by lines. After the hotroller treatment the coagulated binding agent has become fixed, but theuncoagulated binding agent can be removed from a batting simply bywashing it out with water.

Therefore, if the batting shown in FIG. 3 is immersed in running water,only the uncoagulated binding agent is washed away from areas 4a, butthe coagulated binding agent will not be washed away from areas 3a.

The spot-bonded fabric resulting from the washing process is representeddiagrammatically by FIG. 4. The areas 3a containing coagulated bindingagent alternate with areas 4a, which are substantially free of bindingagent. Such a fabric is very soft, elastic and airpermeable. Its waterabsorbency is remarkably high. It is distinguished from the spot-bondedfabrics that have previously been known, by its substantially bettermechanical properties, particularly its tensile strength. It isoutstandingly suitable for further working into artificial leathers,household products, clothing, luggage, lining materials, surfacefabrics, show materials, automobile roof liners, upholstery, floorcoverings, etc.

It should be noted from considering FIG. 4 that one of the majorsurfaces of the spot-bonded fabric, that is, the surface which wasjuxtaposed to the roller having protuberances thereon, does not have aflat profile as do uniformly bonded or unbonded fabrics. Rather, it hashills l0 and valleys 11 which correspond to the bonded and unbondedportions thereof, respectively.

According to one particular embodiment of the invention shown in FIG. 5,a similar product can be produced except that the washing step can bedispensed with, or at least reduced. In this embodiment the batting 3,which is first uniformly impregnated with binding agent, is run betweena pair of rolls 5, 6 (see FIG. 5), both rolls being provided withprotuberances 8 and 9, and 7, respectively. The rolls are rotatedsynchronously so that in the gap between them a protuberance 7 of thelower roll 6 will mesh with and be disposed in an area between theprotuberances 8 and 9 of the upper roll 5, as shown in FIG. 6. As theimpregnated batting 3 passes through the gap between such studded rolls,the pressure distribution is, of course, irregular, and the bindingagent tends to be displaced from the high-pressure areas toward thelow-pressure areas, that is, from the area of smallest gap to the areaof largest gap. Thus the binder tends to be concentrated in the areasbetween the protuberances 8 and 7 or 7 and 9, respectively, while theportion of the fabric directly adjacent each protuberance tends to havelittle or no binder latex left therein. If the roll protuberances areheated as set forth above, substantially all of the impregnated binderwill be coagulated but since the binder latex has also been displaced,the profile of concentration of coagulated binder in the product willalso generally correspond to that shown in FIG. 4. In this embodiment ofthis invention the final product also has a profiled surface. However,in this case the hills, while corresponding to the portions of highbinder concentration, also correspond to those areas of the impregnatedbatting which were between the roller protuberances rather thanjuxtaposed to the roller protuberances as in the embodiment depicted inFIGS. 1 and 2.

In this embodiment, the roll temperature should be kept as low aspossible, for it can be seen that the displacement of the binding agentmust take place before the coagulation begins. If the studded rolls hadhigh temperatures, the coagulation might occur before or during thedisplacement of the binder latex. It is essential to avoid this because,as already stated above once the binding agent has coagulated, it isfixed in place, and then cannot be removed either by pressure or bywashing.

In the embodiment represented in FIGS. 1 and 2, the roll 1 can be at ahigher temperature than in the embodiment of FIGS. 5 and 6 because thepressure in this first embodiment may be substantially less, or evennon-existent, and hence the heat transfer is not as intense as in theembodiment of FIGS. 5 and 6. The contact pressure and the speed of therevolving roll (the contact time) depends upon the pattern of the rollprotuberances and the dimensions of the roll, and on the sensitizationtemperature of the binding agent in the mat. The optimum values in eachcase can, however, be determined quite simply by experiment or.calculation. The minimum temperature of the roll, when considered incombination with the roll speed, must, of course, be high enough toproduce coagulation of the binding agent in the areas 3a directlybeneath the protuberance 2 (see FIG. 2). On the other hand, thetemperature should not be so high as to induce coagulation, at the samerunning speed, in the adjacent areas 4a.

Whereas in the spot-bonding technique that has been practiced hitherto,the binding agent is deposited only locally on the surface of thebatting in the areas where the bonding spots were desired, the newmethod differs from the prior art in that the batting is firstimpregnated quite uniformly as in non-spot-bonding, prior-art fabricproduction methods. This makes it possible to manufacture denser mats.It is readily understood that when binding agent is printed only on thebatting surface, and will then be caused to penetrate through thebatting thickness, only thin mats can be used, since the imprinted dotof binding agent only slightly penetrates into the batting intersticesunderneath it. Deep penetration all the way to the back of the mat, ifpossible is most desired in producing spot-bonded fabrics be causeotherwise the fabric structure, which is not too strong to begin with,may delaminate. It is for this reason that only thin batts having aweight up to 60 g/m have been imprinted by the prior-art spot-bondingmethods, whereas the process of this invention is capable ofspot-bonding batts having fiber weights of up to about l000 g/m or more.

Uniform binder latex impregnations, such as practiced in the method ofthe invention, may be accomplished according to any of the knownprocedures (see, e.g., NONWOVEN FABRICS, published by Non- WovenAssociates, P.O. Box 328, Cambridge 39, 1959, pp 25-28). Theseimpregnations are substantially independent of the thickness of thebatting. It is easily possible to uniformly impregnate batts having afiber weight of 1000 glm In these batts, then, the binder can be made tocoagulate according to the invention at certain points through theentire structure, while other areas in the final product will then berendered substantially free of binding agent.

The spot-bonding method according to the invention, therefore, is notlimited, as is the prior-art spot-bonding method, to thin batting.

The starting batt according to the invention can be produced with a cardor cross lapper or in any other conventional manner. It may be inneedled or unneedled form. The filaments may be staple or continuous andmay be of substantially any conventional fiber material. There are nolimitations with respect to the composition of the fibers or the use ofa multiplicity of different fibers and/or filaments in the same mat. Itcan be said, therefore, that any desired batting can be spotbondedaccording to the process of the invention.

The binding agents to be used according to the invention must, ofcourse, all be coagulatable and in addition, heat coagulation sensitive,i.e., the binding agent present initially in the latex impregnant mustbe capable of coagulating as a function of temperature in the form ofbird-shot when a certain temperature is reached usually between 20 andC.

The invention is of particular value, however, in the production ofimitation leathers comprising a composite of a continuous coating ofsuitable polymeric material joined to one major surface of a non-wovenfabric. There is now often a desire to produce an imitation leather thesurface of which appears to have folds or creases in it, which thusresembles worn leather which has been crumpled. The effect is generallycalled wet leather. Attempts have been made to achieve this effect byapplying a suitable coating of a polymer onto a non-woven fabric,thereby producing a product having a smooth surface; and then crumplingthe composite product so as to give the desired creases in the surface.This product has proven to be somewhat less than satisfactory becauseafter a short time the creases generally disappear and the productregains its smooth surface.

The spot-bonded or line-bonded non-woven fabrics made according to thisinvention, however, are exceptionally well-suited to use in producingsuch creased surfaced wet leather. This is achieved by producing aspot-bonded non-woven fabric according to the practice set forthhereinabove so that the first and second areas, that is, thebindencontaining and binder-free areas, respectively, are arranged in anirregular pattern with at least some of the second areas (i.e., theareas having less or no coagulated bonding agent) being in the form ofelongated irregular streaks. Generally the bonded and the bond-freeareas are arranged in a pattern resembling that obtained in the surfaceof leather or crumpling the leather. A coating of a suitable polymericmaterial such as polyvinyl chloride, is applied to a major surface ofthis non-woven fabric and adhered thereto in the usual way wherebyproducing a resultant imitation leather which has a permanent pattern ofelongated irregular streaks in it. This product has the desired creasedeffect permanently in its surface.

Although any non-woven fabric can be used in the practice of thisinvention, the preferred non-woven fabric is a needled fabric. Thefabric preferably is one that contains shrinkable fibers and which hasbeen shrunk by conventional techniques in order to consolidate it,generally after needling. The area of fabric shrinkage should be atleast 20 percent, and preferably 50 percent or more. The shrunken fabricis then impregnated with coagulatable binder in the manner describedabove and the desired distribution of binding agent achieved. Thedesired polymeric coating can then be applied on the spot-bondednonwoven fabric by any convenient process. For example, a counter coatprocess can be used. In this process a polyurethane or other suitablecoating material is spread on a carrier and the non-woven fabric is thenpressed onto the coating material and the composite so producedsubsequently stripped from the carrier. This type of coating is usuallyglossy.

It may be desirable to additionally crumple the laminated product in aconventional mechanical manner so as to accentuate the veined effectthat is obtained by practing this invention. The veined effect ispermanent.

The following is an Example of the invention.

A fleece consisting of 70 percent of viscose rayon fibers and 30 percentof polyester shrinkable fibers with a total fiber weight of 200 g persquare meter is prepared, needled and then shrunk by heating in theconventional manner. The shrinkage in area is 45 50 percent.Accordingly, the weight of the fabric after shrinking is 440 500 g/sq.m.This shrunk fleece is then uniformly impregnated with a conventionalcommercial heat-sensitive colored polyacrylate latex (Perbunan N 4 Mproduced by Farbenfabriken Bayer) to a wet pickup of latex of about 150percent. Impregnation is by conventional techniques. The impregnatedfleece is then passed through the nip of two heated contoured rollshaving protuberances in the form of irregular longitudinal lines whichresemble veins. The rolls are heated externally to about 250C.

The impregnated latex is thereby first displaced away from theprotuberances into the areas between next adjacent protuberances (seeFIGS. 5 and 6) in accordance with the pattern thereof and the binder isthen coagulated in such location by the heating effect of the rolls. Thetemperature of the rolls and the speed of travel of the fabric throughtheir nip are selected appropriately to achieve the desired effect. Thefabric is thereafter passed through a cold water bath and uncoagulatedbinder and/or auxiliary agents are washed out. After subsequently dryingthe product, a sheet-like structure having the roll pattern on bothsides is obtained.

This product may be split longitudinally if desired, for example, on aconventional leather splitting machine, in order to produce a partiallybonded nonwoven fabric having one profiled surface and one smoothsurface. The upper and lower splits can both satisfactorily be used forthe next stage in the process, just as the unsplit product can so beused.

The next stage in the process is to apply a coating of 50 grams persquare meter of a conventional polyurethane onto the profiled surface bythe counter coat process. After curing, the product is subjected to anadditional mechanical creasing and crumpling operation and thus attainsan irreversible creased effect. This product is excellently adapted touse in the manufacture of, for example, purses, handbags, shoes,clothing, upholstery and the like.

What is claimed is:

1. Process of producing a spot-bonded non-woven fabric which comprises:

A. forming a batting of geometrically randomly disposed filaments orfibers which can be needled and which contain shrinkable fibers;

B. substantially uniformly impregnating such batting with a liquid formlatex containing a temperature sensitive coagulatable binder;

C. contacting said impregnated batting with a heated depth contouredsurface means;

D. heating at least portions of said impregnated batting to an extentsufficient to coagulate at least a portion of said binder from saidlatex into spherules in the interstices of said fabric, wherein thecombination of said steps C and D causes said coagulated binder toconcentrate in predetermined areas in said batting, saidbinder-containing areas of said fabric having a greater thickness thanthe other areas of said fabric, which are vein-like in appearance;

E. washing out substantially all uncoagulated binder from said batting;and

F. drying said batting.

2. Process as claimed in claim 1, including passing said substantiallyuniformly impregnated batting through the nip of a pair of heatedtoothed rollers, each of which has protuberances which alternate withrespect to each other, wherein said protuberances force said impregnatedlatex into the area of said batting between said protuberances, andcoagulating said latex in said areas.

3. Process as claimed in claim 1 wherein said steps C & D are carriedout simultaneously with a contact time of about 1 second at atemperature of about to 420C.

4. Process as claimed in claim 1 including the additional step ofapplying a polymeric film form coating comprising vinyl chloride orpolyurethane to at least one surface of said spot bonded non-wovenfabric which was contacted by said heated depth contoured surface means.

5. Process as claimed in claim 1 including needling the batting producedin step A.

6. Process as claimed in claim 1 including profiling both major surfacesof said batting.

7. Process as claimed in claim 6 including longitudinally splitting saidprofiled, spot-bonded batting between the major surfaces thereof.

8. Process as claimed in claim 7 including applying a polymer coating tothe profiled surfaces of said split batting.

i ig? UNITED STATES PA'iENT 015mm CERTIFICATE Oi? CORRECTION Patent No.3,765,974 Dated October l6,'l974' Inventorun Peter Petersk, and RudolfGaertner -It is certified that error appears in the above-identifiedpatent V and that said Letgers Patent are hereby corrected 55 shownbelow:

Col. 2; line 31 "fiore" should be "most" Col. 35 1ine 34 "and" Should be"an Col. 6, line 10 "4la".should be "4a" vSigned and sealed this 27thday of August 1974.

(SEALl Attest: MCCOY M. GIBSON,-JR. C. MARSHALL DANN Attesting OfficerCommissioner of Patents

2. Process as claimed in claim 1, including passing said substantiallyuniformly impregnated batting through the nip of a pair of heatedtoothed rollers, each of which has protuberances which alternate withrespect to each other, wherein said protuberances force said impregnatedlatex into the area of said batting between said protuberances, andcoagulating said latex in said areas.
 3. Process as claimed in claim 1wherein said steps C & D are carried out simultaneously with a contacttime of about 1 second at a temperature of about 120 to 420*C. 4.Process as claimed in claim 1 including the additional step of applyinga polymeric film form coating comprising vinyl chloride or polyurethaneto at least one surface of said spot bonded non-woven fabric which wascontacted by said heated depth contoured surface means.
 5. Process aSclaimed in claim 1 including needling the batting produced in step A. 6.Process as claimed in claim 1 including profiling both major surfaces ofsaid batting.
 7. Process as claimed in claim 6 including longitudinallysplitting said profiled, spot-bonded batting between the major surfacesthereof.
 8. Process as claimed in claim 7 including applying a polymercoating to the profiled surfaces of said split batting.